Rotating brush type sprayer



June 12, 1951 M. s. ROBERTSON ROTATING BRUSH TYPE SPRAYER Filed Oct. 20, 1947 f v NT N N N MW m v T J A N. O v u I MM N MN I II An I I mll \N NN .N N. KN W \Y R QM Patented June 12, 1951 ROTATING BRUSH TYPE SPRAYER Milton S. Robertson, Campbell, Calif assignor to Independent Crop Dusting, Inc., Campbell, 'Calif., a corporation of California Application October 20, 1947, Serial No. 780,927

2 Claims;

ing spray materials from airplanes; and the broad object of my invention is to provide an improved distributing head for such apparatus.

The invention possesses other objects and features of advantage, some of which, with the foregoing will be set forth in the following description of my invention. It is to be understood that I do not limit myself to this disclosure of species of my invention, as I may adopt variant embodiments thereof within the scope of the claims. 1

Referring to the drawing:

Figure 1 is a view partly in axial section, of my improved spray apparatus, portions of the drive shaft and bearing tube being omitted to shorten the view. 5,

Figure 2 is a bottom View of an airplane showing the apparatus mounted in position under the wings.

Figure 3 is a transverse vertical sectional view showing the inclined impellers in the throat of the distributing head, the plane of section being indicated by the line 33 of Figure 1.

Figure 4 is a plan view of one of the brush spacing disks.

Figure 5 is a plan view of a part of the disk on the leading face of the brush assembly, which disk is the chief element in the present invention.

The spray apparatus embodying my invention comprises a bearing adapted for mounting on an airplane and in which a shaft is journaled. A distributing head is mounted on one end of the shaft for disseminating spray material from the plane, and a propeller is mounted on the other end of the shaft for driving the head. A chamber is provided for feeding spray material to the distributing head, and is preferably formed as an integral part of the bearing. The distributing head is provided with a hollow throat communicating with the chamber, and impellers are provided in the throat for forcing the spray material into the head. An annular brush is provided on the head for disseminating the material; and a baffle disk of special design is fixed to rotate with the brush on the leading face thereof.

In experiments with the spray apparatus which is the subject of my prior Patent No. 2,090,950

dated August 24, 1937, I have discovered how to put an increased volume of spray liquid through the spray brush, and greatly improve the spread of the cone of atomized liquid thrown by the brush. While the brush assembly shown in my the valve lever H.

prior patent has given excellent results and has gone into wide use, it is found that liquid tends to collect on the leading face of the plain disk on the forward side of the brush, due to leakage, or condensation of spray picked up from the air. There is also a tendency for unatomized liquid to form tiny streams along the inner face of the disk instead of passing through the porous section of the brush. Together these two result in the loss of unatomized liquid.

My present invention has to do with means for preventing the formation or accumulation of unatomized liquid on the brush assembly and the resultant waste. It is also concerned with the improvement of the spray pattern thrown by the brush and the atomization and distribution of a greater volume of liquid than has heretofore been possible.

Before describing the distributing head and brush assembly, the structure by which it is mounted and used will be made clear. This comprises a shaft 2, journalled in a bearing tube 3, which is designed to be carried on the underside of an airplane wing 4, being supported on suitable brackets 5. Preferably two spray units are carried, one on each side of the fuselage 6 as shown in Figure 2. A propeller I is mounted on the leading end of the shaft; and a distributing head 8 is mounted on the trailing end.

An enlargement 9 of the tube 3 near the trailing end provides a chamber I 0 to receive the spray liquid just before it passes to the distributing head. The chamber is connected by conduit [2 with a supply tank l3, arranged in the fuselage of the plane. The flow of liquid through the conduit is controlled by the valve 84 operated from the pilots seat by a rod I6 pivoted to When two spray units are used at shown in Figure 2, the rod It is extended to both sides so that both valves are operated together.

The distributing head 8 comprises a hub 2| securely fixed on the tapered end of the shaft 2 by the lock nut 22. The hub carries a rather heavy radial flange 23 from which circumferentially spaced arms 24 extend backwardly to the retaining flange 26 and the cylindrical flange 21, the latter forming a running fit within the rear end of the tube 3 and sealed therein by the gasket and gland 28 threaded on the tube.

The arms 24 provide a mounting for annular wire brushes 30 having radially extending bristles, and which surround the hub and act to disseminate the spray material.

The brushes are of the hollow core type hav- 3 ing the base portions of the bristles clamped between retaining rings 29.

In order to provide passages for the spray material past the compacted base portions of the brushes, the latter are preferably spaced by disks 33 having inwardly extending arms 34 notched at their inner ends to engage the supporting arms 24 of the rotor. Recesses 3? between the arms of the disk provide the passages for conducting the spray material into the loosely disposed outer portions of the bristles.

The brush assembly is held between two plates, one 38, about the same diameter as the brushes lying against the retaining flange 26; and the other 39, of small diameter, pressed against the opposite side of the brushes by the flange 4| of the cap 432, threaded over the end of the flange 23. The plate 39 may be omitted, but is preferably used as a light extension of the flange 4|.

The plate 3.3 plays a very important part in the functioning of the brushes. The plate is conveniently stamped from sheet aluminum with say, three annular beads 45, 4? and t8 spaced as shown in Figure 5. The outer bead it extends toward the wire bristles of the brush, that isrearwardly, and rests snugly against the brush assembly. The other two beads extend forwardly on the leading face of the plate. It will be noted that each of the beads is formed to provide an annular wall 49 lying at nearly 90 with the plane of the face of the plate. In each of these annular walls are apertures preferably about sixteen in each wall and of a diameter of about .040.

Means are provided for forcing the spray material into the hollow core of the rotor and brushes. This is accomplished by providing a plurality of impellers 52 extending outwardly from the hub and spirally so as to operate as a pump to withdraw the spray material from the chamber H3 and drive it into the hollow portions of the rotor. Once introduced between the bristles, the material passes outwardly along the bristles and is thrown radially from the peripheral portions of the brushes. The outward flow of material through the brushes is partly due to the driving action of the impellers, and partly to centrifugal force in the rotating head.

Other forces also contribute to this flow of spray material through the brush. The plate 38 deflects the steam of air flowing against it when the airplane is in flight, reducing atmospheric pressure at the periphery of the brush, and thus increasing the outward iiow of liquid and widening the spray cone thrown. The tiny jets of air through the apertures 5! help the atomizing of the spray liquid. Because some leakage is apt to occur between the rotating flange 2? and the end of the tube; and because in flying back and forth over a field or orchard, the plane is bound to pass through spray previously thrown, spray liquid will collect on the forward or leading face of the beaded and apertured plate. A certain quantity of spray liquid sometimes gets between the inside or rear face of the plate and the bristles of the brush. With an imperforate plate, this liquid on both sides works .out to the periphery and is thrown off in drops rather than in spray. In the apertured plate of the present invention, the jetsof air through the apertures pick up all the liquid which collects against the wall of the bead and carry it inwardly into the brush. On the inside of the plate, a similar action occurs, liquid which otherwise would bleed out along the face of the plate is caught by the jets and blown into the brush assembly where it is thrown outwardly and atomized with the rest.

The net result in using the perforated plate as explained is a more even distribution of spray liquid throughout the. brush, a larger amount of liquid to reach the periphery of the brush, a sub.- stantially complete atomization, and a materially wider cone of distribution.

I claim:

1. The combination with a circular wire spray brush for disseminating spray liquid from an airplane, vof a circular plate substantially covering the leading side of the brush, said plate being provided with a plurality of embossedconcentric beads and having apertures through the beaded portions extending from the outside inwardly and toward the periphery of the brush; 7

2. A spray device for disseminating a spray liquid from an airplane, comprising a circular brush having radially extending bristles in ,combination with a circular plate arranged on the leading side thereof, said plate having a plurality of concentric beads disposed thereon and having a plurality of apertures arranged through the beads.

. MILTON s. ROBERTSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED sTA Es PATENTS Number Name Date 1,542,379 Flaherty s June 16, 1925 2,056,296 Robertson Oct. 6, 1936 2,090,950 Robertson Aug, 24 1937 2,210,846 Aghm'des Aug. .6, 19,40 2,416,226 Schultz Feb. 18, 1 947 FOREIGN PATENTS Number Country Date 347,191 Great Britain Apr- 23; 193;! 

